Spring mounted arc deflector

ABSTRACT

An improved arc deflector having a backing plate, a plurality of spaced-apart walls, and a recessed partition, which members define compartments having an end wall and opposed sidewalls. A set of contacts of an electrical relay are enclosed within each compartment, the walls acting to prevent arcing from one set of contacts to another. A retaining spring seats on a shelf of the backing plate and biases the compartmented enclosure against the relay container to hold the arc deflector immobile during use.

Patented May 18, 1971 3,578,928

2 Sheets-Sheet 1 INVENTORS.

Paw/w J [31/01 v SPRING MOUNTED ARC DEFLECTOR BACKGROUND OF THE INVENTION This invention relates to multiple contact electrical relays and more particularly to a barrier device for preventing arcing and dielectric breakdown in such units.

Miniature electrical relays, such as two and four pole units, areof increasing demand in the electronics industry. The units ordinarily are required to be constructed in extremely small sizes and yet must be capable of withstanding high temperatures, high shock, and strong vibration. Arc barriers are disposed between sets of contacts to prevent arcing between the contacts.

A major obstacle in obtaining effective are deflection arises from the narrow enclosures of the electrical relays. As a result, miniature thin-walled arc barriers are required. The deflectors must not only prevent arcing and dielectric breakdown, but also must be.of sufficient strength to withstand shock and vibration. Present deflectors have failed to provide the required properties, or have done so at prohibitive cost.

STATEMENT OF THE INVENTION In accordance with this invention, arcing between sets of contacts in multiple contact relays and the like is eliminated using a compartmented enclosure having a backing plate and compartment walls, and a retaining spring which seats on a shelf of the enclosure and biases the enclosure against the relay container wall.

The enclosure member is constructed of an electrically resistant material and has compartments defined by the backing plate and a plurality of spaced-apart walls disposed parallel one another. A partition extends perpendicularly across the walls at one end of the backing plate, the partition defining an end wall of the enclosure and being slightly recessed to define a shelf on the backing plate. A retaining spring, such as a simple leaf spring, seats within the shelf portion of the enclosure such that when it is disposed between the partition and the inner wall of the relay it biases the enclosure against the container wall. The enclosure partition separates the spring from the contact compartments such that each set of contacts is separated both from the spring and from the adjoining sets of contacts.

Preferably, the enclosure member comprises a backing plate integrally formed with three compartment walls and a recessed partition provided with semicircular slots for allowing clearance by contact leads when the device is inserted in the relay. The three spaced-apart walls define apair of compartments. The unit serves as an arc deflector in a two pole type electrical relay. It is inserted at the bottom of the relay with the partition adjoining the bottom inside wall of the relay, the backing plate being flush with the rim of the relay such that a container can be readily inserted over the working components of the relay to complete the unit.

The enclosure member and retaining spring of this invention constitute an extremely effective are deflector for use in the smallest electrical components. The devices are especially useful in multiple contact electrical relays and the like where high dielectric properties are required in a minimum amount of space. The are deflector can be integrally formed in accordance with rapid and economical fabrication processes and adapted for utilization in electrical units subject to extreme shock and vibration as well as high temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the enclosure member;

FIG. 2 is a fragmentary bottom view of an electrical relay showing the partitioned end of theenclosure member and the retaining spring; and

FIG. 3 is a fragmentary end view of the relay shown in FIG. 2 taken on line 33. I

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I is a perspective view of the arc deflector removed from an electrical relay and absent the retaining spring. The enclosure member 10 has three opposed sidewalls I2, l4, 16, the outer end walls of which abut the inner sidewalls of the relay housing. The backing plate 18 of the enclosure member is flush with the relay container as shown in FIG. 2. The middle wall 14 divides the enclosure into a pair of compartments, each compartment enclosing a set of the relay contacts. A ridge 21 extends across one end of the enclosure member. A recessed partition 20 extends across the other end of the enclosure between the two end walls thereof. The partition 20 is recessed to define a shelf 22 on the backing plate 18 and has semicircular slots 24 at its upper end for accommodating header terminals connected to the contacts.

FIG. 2 shows the enclosure member 10 of FIG. 1 disposed within an electrical relay 26. A leaf spring 28, for example, consisting of a single, arched member, is seated on the shelf 22 defined by the partition 20 and the backing plate 18 of the enclosure member. The spring, having a contacting tab 23 welded or otherwise secured to the relay header 36, biases the enclosure member against the container can or cover 30 after the enclosure member has been inserted in the relay and the can has been placed in covering position.

As shown in FIG. 3, the retaining spring 28 seats on the shelf 22 of the backing plate 18 along the outer side of the partition. The set of contacts 34 is thus separated from the adjoining set and from the retaining spring. The contacting tab 23 of the spring 28 is secured to the base of the relay header 36. The bottom of the backing plate is urged by the retaining spring against the container can 30 of the relay, thereby securely holding the arc deflector in position during the most severe shock and vibration. A notch 35 in the sideplate 37 keeps the arc deflector "from moving in a transverse direction. As a result, arcing is contained within the arc chambers of the deflector.

The enclosure member is integrally formed of a Micalex, ceramic, or other suitable dielectric material of substantial structural strength and high temperature resistance. The dielectric properties are thus preserved in the least amount of space and the deflector can withstand high temperatures without damage or warpage. Two or more of the enclosure members can be used together in a single electrical relay to provide arc chambers for a plurality of adjoining contact sets.

It will be seen that the above-described arc deflector arrangement permits easy assembly of the relay. Before the cover is attached, the deflector is inserted in position and pressed inwardly against the spring with the edges of the walls -and backing plate against the base of the relay. The cover is slipped over the relay and the deflector is released, permitting the spring to urge the deflector against the inside of the cover where it is secretly held against vibration and shock. The deflector shields the contacts from the frame and cover, preventing arcing from the contacts to the frame or cover.

We claim:

1. An electrical switching assembly comprising a base member through which electrical leads pass for external connection, stationary contacts mounted on said leads, a cover which fits over the base and is secured thereto to form a fully enclosed space for the contacts, a shield member of dielectric material having a backing plate, a plurality of spaced-apart parallel walls extending from the backing plate, the two outermost walls and the backing plate having one edge thereof lying in a common plane and a partition extending between the walls and joined to the backing plate, the partition being positioned parallel to but spaced slightly from said plane, and a spring member secured to the base adjacent the cover, the shield member being positioned within said space with said one edge of each of the walls and the backing plate lying in said plane slidably engaging the base, the partition passing over the spring member and the spring member engaging the backing plate in the space between the partition and the base to urge the backing plate against the cover, the partition extending over the spring member to shield the contacts from the spring member and base.

2. The assembly of claim 1 wherein the partition is formed with slots extending between each pair of adjoined walls of the shield member, the slots being open at the edge of the partition remote from the backing plate, the slots receiving the electrical leads extending through the base when the shield the open slots toward the backing plate so that the partition shields the contacts from the base. 

1. An electrical switching assembly comprising a base member through which electrical leads pass for external connection, stationary contacts mounted on said leads, a cover which fits over the base and is secured thereto to form a fully enclosed space for the contacts, a shield member of dielectric material having a backing plate, a plurality of spaced-apart parallel walls extending from the backing plate, the two outermost walls and the backing plate having one edge thereof lying in a common plane and a partition extending between the walls and joined to the backing plate, the partition being positioned parallel to but spaced slightly from said plane, and a spring member secured to the base adjacent the cover, the shield member being positioned within said space with said one edge of each of the walls and the backing plate lying in said plane slidably engaging the base, the partition passing over the spring member and the spring member engaging the backing plate in the space between the partition and the base to urge the backing plate against the cover, the partition extending over the spring member to shield the contacts from the spring member and base.
 2. The assembly of claim 1 wherein the partition is formed with slots extending between each pair of adjoined walls of the shield member, the slots being open at the edge of the partition remote from the backing plate, the slots receiving the electrical leads extending through the base when the shield member is in operative position.
 3. The assembly of claim 2 wherein the stationary contacts are offset from the electrical leads in a direction toward the backing plate and the cover, the contacts extending beyond the open slots toward the backing plate so that the partition shields the contacts from the base. 